Optical navigation sensors are conventionally used for surface navigation applications. For example, conventional optical navigation sensors are implemented in optical mouse devices for desktop computers. In surface optical navigation, the optical navigation sensor tracks the features of the navigation surface by generating and comparing several images of the navigation surface.
More recently, as computers have become more prevalent for the viewing of internet pages, long documents, etc., additional tactile interface controls such as the scroll wheel have been added to the conventional optical mouse components. The functionality of the scroll wheel serves to increase the user's ability to interface with the device. However, with the addition of the scroll wheel to the optical mouse, internal components are required to detect the user input to the scroll wheel. These components occupy internal space within the device and contribute additional factors for component failure. Although some conventional devices use a separate image sensor to detect a scroll wheel movement, the power requirements of the device are increased by implementing additional sensors. The cost of manufacture and assembly also increases with the integration of additional processing components.